Several radiation measurement technologies currently exist including Themoluminescent (TLD) dosimeters, Optically Stimulated Luminescence (OSL) dosimeters, electronic dosimeters, and quartz or carbon fiber electrets.
Optically Stimulated Luminescence (OSL) dosimeters use an optically stimulated luminescent material (OSLM) (i.e. carbon doped aluminum oxide) to retain radiation energy. Tiny crystal traps within the OSL material trap and store energy from radiation exposure. The amount of radiation exposure is determined by shining a light of one color (i.e. green) on the crystal traps and measuring the amount of light of another color (i.e. blue) emitted. Alternatively, pulsed light stimulation can be used to differentiate between the stimulation and emission light [there is a patent for this, held by Stephen McKeever, See, U.S. Pat. Nos. 5,892,234 and 5,962,857, issued to McKeever et al. Unlike TLD, OSL systems provide readouts in only a few seconds and provide multiple readouts since only a very small fraction of the exposure signal is depleted when read out. In current dosimetry programs based on OSL and TLD dosimeters, the dosimeters are returned to a processing laboratory for readout.
One of the problems with state of the art OSL systems is that the filters used within the dosimeters are too thick for use in a thin, credit card sized dosimeter. For more information on OSL materials and systems, see, U.S. Pat. No. 5,731,590 issued to Miller; U.S. Pat. No. 6,846,434 issued to Akselrod; U.S. Pat. No. 6,198,108 issued to Schwietzer et al.; U.S. Pat. No. 6,127,685 issued to Yoder et al.; U.S. patent application Ser. No. 10/768,094 filed by Akselrod et al.; all of which are hereby incorporated by reference in their entireties. See also, Optically Stimulated Luminescence Dosimetry, Lars Botter-Jensen et al., Elesevier, 2003; Klemic, G., Bailey, P., Miller, K., Monetti, M. External radiation dosimetry in the aftermath of radiological terrorist event, Rad. Prot. Dosim, in press; Akslerod, M. S., Kortov, V. S., and Gorelova, E. A., Preparation and properties of Al2O3:C. Radiat. Prot Dosim 47, 159-164 (1993); and Akselrod, M. S., Lucas, A. C., Polf, J. C., McKeever, S. W. S. Optically stimulated luminescence of Al2O3:C. Radiation Measurements, 29, (3-4), 391-399 (1998), all of which are incorporated by reference in their entireties.
A need exists for a very thin combined equilibrium and energy compensation filter for OSLM dosimeters and dosimeter incorporating such filters.